Packet radio communications system

ABSTRACT

A packet radio communications system comprises a core network comprising packet data networks, each including network communications elements to communicate packets using an internet protocol transport plane, and a common gateway support node. The gateway support node routes packets via communications bearers established through packet data networks using network communications elements. The system includes radio access networks, to provide radio access bearers, for communicating packets between mobile user equipment. A packet service control subsystem function comprises an access network part and a non access network part. The access network part controls communication of packets via radio access bearers and the non-access network part controls communication of packets via communications bearers. At least one radio access network operates with a different telecommunications standard than the other radio access networks, and at least one packet data network operates with a different telecommunications standard than the other packet data networks.

FIELD OF THE INVENTION

The present invention relates to packet radio communications systems forcommunicating internet packets to and/or from mobile user equipment.

BACKGROUND OF THE INVENTION

For the communication of data packets, packet radio communicationssystems such as the General Packet Radio Service (GPRS) haven beendeveloped. GPRS provides support for a packet-orientated services and isarranged to optimise network and radio resources for packet datacommunications. For example, GPRS networks can provide a facility forsupporting internet protocol services to mobile user equipment. The GPRSprovides a logical architecture, which is related to the circuitswitched architecture of a mobile radio system.

Internet protocol communications have become prevalent as a means forcommunicating data efficiently and conveniently. However the growth ofinternet protocol based services has introduced new demands on networkswhich operate in accordance with GPRS. It is therefore desirable toenhance packet radio communications systems, like GPRS, to make themmore flexible and better able to cope with a rapid growth in internetprotocol data traffic and internet protocol based services.

SUMMARY OF INVENTION

According to the present invention there is provided a packet radiocommunications system for communicating internet packets to and/or frommobile user equipment. The system comprises a core network comprising aplurality of packet data networks, each including network communicationselements operable to communicate internet packets using an internetprotocol transport plane, and a common gateway support node. The gatewaysupport node is operable to route the internet packets viacommunications bearers established through the packet data networksusing the network communications elements. The system includes aplurality of radio access networks connected by the internet protocoltransport plane to the core network components of the packet datanetworks for communicating the internet protocol packets to and/or fromthe mobile user equipment. Each of the radio access networks is operableto provide radio access bearers for communicating the internet packetsto and/or from the mobile user equipment. The system includes a packetservice control subsystem function comprising an access network part anda non access network part. The access network part is arranged tocontrol the communication of the internet packets via the radio accessbearers and the non-access network part is arranged to control thecommunication of the internet packets via the communications bearersusing the network communications elements of the packet data networks.At least one of the plurality of packet data networks is arranged tooperate in accordance with a different telecommunications standard thanthe other packet data networks.

Embodiment of the present invention can provide a packet radiocommunications system is arranged to support a prevailing use ofinternet protocol based networks, and an ever changing and increasinguse of internet protocol based services and internet protocol networkingand transport technologies. To this end, a packet radio communicationssystem according to an embodiment of the present invention can provide acommon gateway support node through which communications bearers areestablished across a plurality of packet data networks via networkcomponent elements. The network elements, which form the packet datanetworks, are formed from standardised GPRS components andnon-standardised GPRS and/or evolving packet radio system networkcomponents, which may operate in accordance with an evolving 3GPPstandard. To unify communication via the different packet data networksand to provide control and policy enforcement from a common gatewaysupport node, a common internet protocol transport plane is utilised forestablishing communications sessions via the packet data networks.Furthermore, in some examples, a plurality of different types of radioaccess network may be provided to facilitate mobile access to internetprotocol based communications and services such as Internet ProtocolMulti-media Sub-systems (IMS) services from a variety of locations andenvironments. The packet radio communications system is thereby arrangedto cater for rapid growth of internet protocol traffic, by, for example,providing heterogeneous radio access networks for internet protocolbased services.

In some examples a common packet communications bearer may be shared bya plurality of mobile user equipment, such as for example where a HighSpeed Down-link Packets Access service is being provided. For the commoncommunications bearer, a common packet data protocol context may beprovided from the gateway support node.

Various further aspects and features of the present inventions aredefined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only with reference to the accompanying drawings where likeparts are provided with corresponding reference numerals and in which:

FIG. 1 is a schematic block diagram of a packet radio communicationssystem;

FIG. 2 is a schematic block diagram illustrating in more detail parts ofthe packet radio communications system shown in FIG. 1;

FIG. 3 is a schematic block diagram providing a simplifiedrepresentation of the parts of the packet radio communications systemshown in FIG. 2;

FIG. 4 is a schematic block diagram illustrating the function of apacket service control subsystem, which appears in the packet radiocommunications system of FIG. 1;

FIG. 5 is a schematic blocks diagram illustrating reference pointsdefining signalling interfaces and inter-action parts of the packetradio communications system shown in FIG. 1;

FIG. 6 is a schematic representation of network components forming partof a core network shown in FIGS. 1 and 2, illustrating a plurality ofmobile user equipment establishing packet data protocol contexts,including common packet data protocol contexts, which can communicateusing a common packet communications bearer;

FIG. 7 is a schematic representation of parts of the packet radiocommunications system of FIGS. 1 and 2, providing separate packetcommunications bearers to two of the mobile user equipment shown in FIG.6, which share a common packet data protocol context;

FIG. 8 is a schematic representation of parts of the packet radiocommunications system of FIGS. 1 and 2, providing a common packet databearers for supporting Internet protocol communications to and/or fromtwo of the mobile user equipment shown in FIG. 6, which share the commonpacket data protocol context; and

FIG. 9 is a schematic representation of parts of the packet radiocommunications system of FIG. 8, illustrating the operation of the radionetwork controller to communicate internet packets to the two mobileuser equipment which share a common packet data protocol context and acommon packet data protocol bearer, using a radio access bearer filter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The Basic Network Elements

There are four major network elements in the architecture;

-   -   The access networks: including the existing 3GPP        RAN—UTRAN/GERAN, the evolved 3GPP RAN/LTE, the non-3GPP Access        Networks    -   The Packet Core Networks: including both the existing Packet CN        and the evolved Packet CN. The separating of the two in the        depiction does not mean separate CN architecture, functions and        network elements. The existing packet CN should be re-used at        maximum with possible functional extensions and enhancements.    -   The Packet Service Control Subsystem    -   External networks

FIG. 1 provides an illustration of a system architecture in accordancewith an example embodiment of the present invention. In FIG. 1 a corenetwork part comprises core network components according to an existingtelecommunications standard such as 3GPP and core network parts 4 whichoperate in accordance with a non-specified or proprietary standard. Thecore network components are linked by a gateway support node 6, which iscommon to the packet data networks which form the core network. The corenetwork components are linked by an internet protocol transport plane 8via which data is communicated between the network elements. The corenetwork components communicate user and signalling data via fixed linemedia between external networks 10 and radio access networks 12, 14, 16.The first of the radio access networks 12 operates in accordance withexisting 3GPP access network standards and include as will be explainedshortly, radio network controllers RNC and node B's to perform aUniversal Terrestrial Radio Access Network (UTRAN) interface with themobile user equipment. In contrast the second radio access network 14operates in accordance with an evolved 3GPP access network standard suchas RANLTE. The third radio access network 16 operates in accordance witha wireless local area network such as IEEE 802.11B otherwise known asWiFi. The control of communication, resource allocation and mobilitymanagement is controlled by a packet service control sub-system 20.

The packet service control sub-system 20 is arranged to control thecommunication of internet packets via the core network between theexternal network and the mobile user equipment via the radio accessnetwork to which the user equipment is attached. The packet servicecontrol sub-system 20 comprises an access part 22 and a non-access part24, which are controlled by a policy control function 26. The AccessPart 24 is for controlling the access networks and the Non-access Part22 is for controlling the core networks and the inter-working functionsin the gateway. The Access Part 24 provides the control such as resourceallocation and access, the access network selection, QoS, etc. TheNon-Access Part 22 provides the control functions with regard to theApplication/Service/Session levels in terms of Service/Bearer AccessAuthorisation, Session Control and Management, QoS (incl. QoSinteractions with external networks), Resource access control, Charging,Legal Interception, and interworking with external networks.

The external networks 10 include Internet, Public/Private IP networks,3GPP/non-3GPP PLMN's, and PSTN, etc.

The Reference Points

There are four reference paints are described in the architecture:

-   -   The Access Part Reference Point: including the control functions        (access selection, resource allocation/access, QoS,        handover/mobility, etc) for access networks IL    -   The Non-Access Part Reference Point; including the control        functions (service/session/UMTS bearer access authorisation,        IP/session Mobility, QoS inter-working, security etc) 12.    -   The Interworking Reference Point: including the transport        functions of user data between the 3GPP PLMN and the external        networks 13.    -   The Access—CN Reference Point: including the transport functions        of user data between the access networks and the packet core        networks 14.

It is noted that the above baseline architecture does not impose anyrestrictions with regard the functional split and the correspondinginterface definitions between and within the access networks and thepacket core networks.

Communication of both user data and signalling data between therespective parts of the system architecture shown in FIG. 1 is shown inaccordance with reference points for interfaces which specify thefunctional interaction between the elements. The first reference pointis the access part reference point I1 which specifies exchange ofmessages and interface between the access part of the policy of thepacket service control sub-system and the radio access networks 12, 14,16. The second access reference point 12 specifies the signallingexchange and interfaces between the non-access part of the packetservice control sub-system 20 and the core network components. The thirdinterworking reference point 13 specifies the message and signallingexchange between the gateway support node 6 and the external networks10. The fourth access core network reference point 14 specifies thesignalling messages and interface exchange between the radio accessnetworks 12, 14, 16 and the core network components 4.

An example of the core network and radio access network components ofthe system architecture shown in FIG. 1 is provided in FIG. 2. In FIG. 2the gateway support node 6 is connected to a serving GPRS support node(SGSN) 40 as well as evolved serving GPRS support nodes (SGSN+) 42, 44,46. The SGSN 40 and the SGSN+ 42, 44, 46 form parts of four differentpacket data networks PDN1, PDN2, PDN3, PDN4. The evolved serving GPRSsupport nodes SGSN+ operate in accordance with an evolved 3GPP standard,a proprietary standard or indeed any other operative component whichserves to route interne packets via fixed line media components to radioaccess network components. As shown in FIG. 2 the SGSN 40 of aconventional GPRS network is connected to a radio network controller(RNC) 48 which is provided with two node-B's 50, 52 which provide aUTRAN radio access interface for communicating with a mobile userequipment 54. Two of the non-standard SGSN 42, 44 are connected tonon-standard RNC's 58, 60 which are provided with non-standard node-B's62, 64, 66. The non-standard node-B's 62, 64, 66 provide a radio accessinterface in accordance with a non-3GPP access standard or an evolved3GPP access network/RANLTE standard. The non-standard node-B's 62, 64,66 provide a radio access interface to mobile user equipment inaccordance with the evolved standard.

In contrast the remaining SGSN 46 which operates in accordance with anon-3GPP standard is provided with a WiFi access gateway 70 whichprovides a radio access interface in accordance with IEEE 802.11 to amobile user equipment 72. The radio access gateway 70 therefore formspart of a non-3GPP access system 16 shown in FIG. 1.

The core network components and the radio access network componentsshown in FIG. 2 are also shown in FIG. 3 in a simplified representationillustrating the connection of each of the three different networksshown in FIG. 2 to the gateway support node 6. As illustrated in FIG. 3each of the core network components which is the SGSN 40, thenon-standard SGSN+ 42 and the non-standard SGSN+ 46 are connected via anon-access reference point 12 to the non-access part 22 of the packetservice control sub-system. Also shown is the access part 24 of thepacket service control sub-system 20 which is connected via a referencepoint I1 to the components of the radio access network. These componentsare the GPRS standardised radio network controller RNC 48, the Node-B 50and the evolved 3GPP standardised components which are the RNC+ 60 andthe Node-B+ 66 as well as the non-3GPP radio access gateway which is theWireless LAN 70. As illustrated in FIG. 3 a common unifying aspect ofthe components of the system architecture is that they are all arrangedto operate to communicate internet packets via an internet packettransport layer 80, 82, 84. All of the core network components alsoconnect to the gateway support node 6.

FIG. 4 provides an illustration of the operation of the packet servicecontrol sub-system and the reference point interfaces I1 between theaccess part 24 and an access network such as the evolved radio accessnetwork 14 I1. Also shown is the interface between the non-access part22 and the packet core network 6. The access part 24 operates to controlthe radio access network and performs a selection policy to select anappropriate one of the access networks. The interface I1 thereforesupports interactions between the packet data protocol performed in theaccess part and a policy enforcement point which is a point in the radioaccess network for enforcing resource control. Accordingly, signallingfunctions which are used and specified as part of the reference pointare:

-   -   Access network selection    -   Mobility management    -   Resource allocation and access    -   Call admission    -   Load balancing    -   Quality of service implementation

In contrast the non-access part 22 is arranged to control the packetcore network 6 to the effect of identifying the appropriate packet dataprotocol context which should be activated for a particularcommunications session and the appropriate bearer which should beimplemented to provide that communication session. Accordingly thereference point 12 therefore specifies signalling and interaction toenforce packet data policy on the PDP contexts and the packet bearerselection.

FIG. 5 provides an illustration of the reference points between theexternal network and the core network 13 and the access networks and thecore network components 14. The interworking reference point 13specifies an appropriate map between the quality of the servicespecified in accordance with the internet protocol and a quality ofservice which is provided on the network such as conversational,streaming, interactive and background. Thus the internet protocolquality of service is specified in the differential service header fieldidentifying, Assured Forwarding (AF) Expedited Forwarding (EP) and BestEffort (BE) are mapped into the corresponding UMTS QRS class. Incontrast, the access core network reference point 14 is arranged tospecify a mapping between the packet communication bearer established onthe core network parts with respect to the radio access bearers providedby the radio access networks 12, 14, 16.

The General Design Principles for the Baseline Architecture

In this section, the architectural role of the access networks, thepacket core networks, and the Packet Service Control networks/subsystemsare analysed in terms of the above three major functions.

The Design for the Access Networks

The general trend for the evolved access networks are reflected in thefollowing aspects:

-   -   Emerging faster and more efficient wireless/wireline access        technologies.

New radio and wireline technologies are becoming available to providemore efficient and higher access speed such as xDSL, 802.16e, MIMO, OFDMetc. The evolved access networks should consider those new emergingaccess technologies and its integration with existing 3GPP accessnetworks. The design and functional split of radio access protocol stackand procedures should not compromise the efficiency and the performanceimprovements as brought by those new technologies.

Co-Existing and Complementary Coverage of 3GPP and Non-3GPP DefinedAccess Networks

To maximise the service accessibility and continuity from 3GPPoperators, those non-3GPP defined access technologies and networksshould be taken as an important complementary coverage for 3GPPoperators' services. Therefore, efficient, flexible, reliable and yetoperator controlled interworking, mobility, and roaming with thosenetworks should be supported. A typical example of this complementarycoverage is the WLAN Interworking functions as defined in 3GPP. Afurther enhancement and extension of this concept should be consideredfor existing and future wireless/wireline access technologies.

Access to be Provided as a Form of Service

In addition to the conventional concept of provisioning the serviceswith regard to the media contents, the access networks may well need tobecome an important means to provide “transport services” for access toboth 3GPP and non-3GPP operators' defined services. This will be underthe control of 3GPP operators. One of the direct consequences of thisevolved access service is the re-thinking of Bearer Service AccessControl and the Charging functions. In addition, this “access serviceprovisioning” should apply to both 3GPP and non-3GPP defined accessunder the general framework for 3GPP operator controlled access.

Centralised Vs. Distributed Control Over the Radio Access and RadioResource Management

Up to the release 5, the radio access control and radio resourcemanagement is centralised within the RNC's in UTRAN. To improve thecontrol and the transport efficiency and accommodate high speed and morespectrum efficient radio access technologies, the functions of RNCversus that of Node-B need to be re-considered. In Release 6, thesupport of HSPDA/HSUPA already requires some of the key radio resourcecontrol functions such as packet scheduling be located within theNode-B. This Node-B based localisation of radio access and resourcecontrol is perceived to become one of the important measures to improvethe control and transport efficiency and the associated performance, inparticular, the reduction of control and transport latencies, in theevolved 3GPP radio access network infrastructure. This will also bebeneficial to the elimination of performance bottleneck as caused by thebackhaul links and the reduction of both Capex and Opex.

Architectural Split Between Control and Transport Functions

In addition to the perceived benefits of locating the radio access andresource control functions to the very edge of the radio access networksuch as the Node-B's, the issues of more efficient management of controlfunctions such as radio set-up, configuration/re-configuration,maintenance and release will need to be considered due to their directimpact on the over-all end-user perceived service quality (e.g. callset-up time) and the complexity as well as the associated cost in bothdeployment and operations (Capex and Opex) of the radio access networks.

Further evolution from the existing joint-locations of the control andtransport functions (within both Node B and RNC's) to separate controland transport entities is predicted to be beneficial to thesimplification of the radio access network infrastructure and thetransport layer functions which, in turn, help improve the control andtransport efficiency and performance. In addition, separation of controland transport entities will also facilitate the introduction of new morespectrum efficient radio access technologies, integration and theconvergence of fixed and wireless access technologies and the sharing ofa common IP transport network between the access networks, packet corenetwork and the packet service control networks.

Maximum Optimisation for IP Traffic

Due to the relatively low efficiency and resource utilisation u inmanaging and the transporting the IP-based traffic in comparison to thatfor circuit-switched traffic, the radio access networks will need to beadapted and optimised to support LP traffic, in particular, thereal-time IP traffic which features short payloads and relatively largeprotocol overheads which have adversely affected both the transportefficiency and end-to-end QoS.

The evolved radio access networks should be able to support IP traffic,in particular, the real-time IP traffic with efficiency and qualitycomparable to that for the circuit-switched traffic. Two of the typicalmeasures, for instance, are the more efficient and robust headercompressions and the support of AMR/Unequal Error Protections forreal-time IP traffic.

The Design for the Packet Core Networks

The evolution of 3GPP Packet Core networks should consider the followingissues.

More Efficient Control and Transport Functions with Reduced Complexityand Enhanced Scalability

The packet core network serves as the “anchor point” for many importantfunctions such as UMTS session management, user subscription,authorisation, authentication, location management, mobility management,charging, inter-working between heterogeneous access networks (3GPP and3GPP access networks, fix and mobile convergence) and external networks(e.g. Internet, 3GPP and non-3GPP PLMN's), etc. The complexity of thoseoperations contributes to difficulties in achieving overall highend-to-end control and transport efficiency and performance and reducingthe cost for deploying and the operating the networks. Measures shouldbe taken to further optimise both the control and the transportfunctions in the evolved packet core network architecture. For instance,the per session based bearer management and QoS management may needfurther evolve to improve the system scalability and the general systemefficiency and performance.

Simplification of Packet Core Network Infrastructure

It is necessary to evaluate the existing 3GPP packet core networks(SGSN/GGSN based) infrastructure and study the need and benefits as wellas the impact of reducing the number of intermediary network elementsand the number of open interfaces and reference points. This is foreseento be beneficial to improving the control and transport efficiency andthe performance as well as reduction of both Capex and Opex.

Efficient Support of Multi-Access to Heterogeneous Access Technologies

The packet core network serves as the anchor point of interworking,selection, and access and mobility control across heterogeneous accesstechnologies. The packet core network should be able to support thecontrol and management of EP traffic going to and coming from theheterogeneous access networks with 3GPP operators' centric control interms of access selection, security, mobility, QoS, etc.

Maximum Optimisation for IP Traffic

The packet core network should present as few control and trafficmanagement points as possible for both incoming and out-going TI)traffic. Considering the potential complexity of reducing the IPprotocol related transmission and processing overheads, the IPperformance optimizations functions such as header compression may wellbe located within the core network to reduce the complexity and the costin the radio access networks and improve the over-all end-to-endperformance.

Minimise IP Protocols Specific Control and Transport IPv4 vs. IPv6

Many of the existing UMTS control functions are IPv4 and IPv6 specific.For instance, the UMTS session management (PDP Contexts and TFToperations) are dependent on which version of IP protocol is used. TheUMTS CN bearers, as a result, can only carry IPv4 or IPv6 traffic eventhough the UMTS CN bearers are subsequently encapsulated within theunderlying EP transport networks. This will restrict the flexibility ofIP-based service access and increases the complexity of the control andmanagement functions and the compromise the scalability.

Efficient Support of IPv4 and IPv6 Transitions

The gradual introduction of IPv6-based services, even IPv6 networkelements, into 3GPP PLMN's, is inevitable. While most, if not all, ofcurrent 3GPP PLMN's operates based on IPv4. Although the existing 3GPPsystem Architectures are designed to support both IPv4 and IPv6, thereis lack of analysis and study in 3GPP on the effective and low-impact(low cost, undisrupted operations/services) transition mechanismsbetween IPv4 and IPv6 based 3GPP networks and services. Lots of progresshas been made in some working groups in IETF which should be used asimportant references on the subject.

Flexible and Reliable Inter-Operability with Existing 3GPP Systems

The evolved 3GPP architecture and the improved system functions areexpected to provide more efficient support of IP-based services. Carefulconsiderations should be made in making the evolved systemsinter-operable with the existing systems and, in the meantime, allowsfor maximum flexibility as controlled by the operators in directing theIF traffic across the appropriate packet core and access networks basedon operators' defined policies.

Interworking with Fixed Networks and Non-3GPP Wireless Networks

Efficient and reliable inter-working should be supported with fixednetworks and non-3GPP defined PLMN's and wireless networks. Thisinter-working is differentiated from the multi-access support forheterogeneous access technologies as discussed above in that the fixednetworks and non-3GPP PLMN's and wireless networks are “external” to theevolved 3GPP system. These interworking functions will be located withinthe 3GPP PLMN gateway.

The Design for the Packet Service Control Subsystem

The packet service control subsystem provides the control and managementof services such as security (authorisation & authentication, userdata/information integrity and privacy etc), IP-based session management(e.g. IP Multimedia Session), policy control for QoS, mobility, accessselection and resource access control, etc. The packet service controlsubsystem is operationally independent of both the access networks andthe packet core network but may exercise the direct control over theoperations within the packet core networks and the access networks.

Effective Control Over the Access and Packet Core Networks

The evolved system architectures for both access networks and the packetcore networks are expected to enable the operators to provide effectivecontrol based on their policies on network resources allocation andaccess, QoS, handover and mobility between 3GPP defined networks as wellas across 3GPP and non-3GPP defined networks, roaming, service accessauthorisation in both roaming and non-roaming situations for servicesprovided by both home PLMN's, the visited PLMN's as well as the thirdparty service providers.

The control is also expected to work on an end-to-end basis with other3GPP and non-3GPP defined networks in terms of security, QoS, serviceaccess, etc.

Easy and Flexible Integration with IT-Based Service Creation andControl.

This is to take the advantage of the quick and more effective newservice introductions as often seen in IT industries which can implementthe defecto (widely accepted and used) standards for IP-based serviceswithin a short period of time.

Maximum Re-Use of Existing IP Service Related Protocols and Standards

Due to the many common requirements from both 3GPP operators and ISP'son the control and management of IP-based services, the evolved packetservice control subsystem should consider re-using the existing IPprotocols as defined in IETF such as SIP with extensions, AAA, IPSec,Policy Framework, QoS Framework/NSIS and JP Mobility Management (MobileIP) etc, where it is applicable. This will reduce the amount of the workand time and facilitate the integration with non-3GPP specific servicecontrol.

Example Illustration of Co-Existence of Different PDP Contexts

FIGS. 6, 7, 8 and 9 provide an illustration of the operating of thepacket radio communications system shown in FIGS. 1 to 5, operating toestablish a common packet data protocol context for establishing andcontrolling access to a packet data communications bearer. As will beexplained, the packet data communications bearer may be a commoncommunications bearer in that is shared by more than one mobile userequipment and/or that different communications session which operate inaccordance with different internet protocol versions use the bearer.

FIG. 6 provides an example illustration of an arrangement in which aplurality of UEs have established PDP contexts using the networkcomponents of the communications system shown in FIGS. 1, 2 and 3. Twoof UEs have established a common PDP context. As shown in FIG. 6, threeUEs UEa, UEb, UEc are communicating internet protocol packets across theGPRS network. Two of the mobile user equipment UEa, UEb have establisheda common GPRS bearer 90. For example the first mobile user equipment UEamay establish the common GPRS bearer by performing a PDF contextactivation request specifying that the PDP context should be a commonPDP context as described above. The gateway support node 6 thenestablishes a common PDP context 100 for the first UE UEa. The first UEUEa then establishes in combination with the gateway support node 6 atraffic flow template TFTa which includes in the parameter list a commonPDP address type. For the example shown in FIG. 6 the first mobile userequipment UEa specifies that the internet protocol address which it willuse for its communication session is an IPv4 address. Thus the commonPDP address type specified by the TFTa is an IPv4 address as illustratedfor the TFTa 102 for the parameter list 104.

The second UE UEb also sets up a common PDP context with the gatewaysupport node 6. Since the common PDP context 100 has already beenestablished by the first UE UEa, then the gateway support node 6 isarranged to join the second UE UEb to the common PDP context. However, aseparate common PDP context 100 is associated with a TFT for the secondUE which is a TFTb. TFTb also specifies that the packet filter componentis a common PDP address type and for the second UE an IPv6 address isspecified as the filter component in a field 108. Thus, each mobile userequipment UEa, UEb, UEc, establishes its own TFT. In contrast, the thirdUE UEc request a conventional primary PDP context activation for its owndedicated GPRS bearer 112. The third mobile user equipment UEc mayestablish a secondary PDP context 112 which is also arranged tocommunicate IP packets via a GPRS bearer although only one 112 is shownin FIG. 6. For the third UE UEc a TFTc 114 is established in order tofilter packets to either the primary or the secondary PDP context inaccordance with a conventional arrangement. Thus as illustrated in FIG.6 two of the mobile user equipment UEa, UEb are communicating via acommon GPRS bearer 90 using a common PDP context 100 although each hasits own traffic flow template TFTa, TFTb. In an alternative arrangementthe first and second UEs UEa, UEb may establish separate GPRS bearers90, 114 and communicate internet packets via these separate bearers eventhough they share a common PDP context.

Common GPRS Bearer

There are two possible scenarios for the first and second mobile userequipment UEa, UEb of the example represented in FIG. 6 to communicatevia the GPRS network 1 using the shared common PDP context. One exampleis shown in FIG. 7. In FIG. 7 the gateway support node 6 establishes aseparate GPRS Tunneling Protocol (GTP) bearer GTP_UA, GTP_UB for each ofthe first and second UEs UEa, UEb. As shown in FIG. 7 although the firstand second UEs share a common PDP context, the internet protocol packetsare communicated across the GPRS network via separate GTE bearers. Whenthe internet protocol packets reach the RNC 60 for communication via aRadio Access Bearer (RAB) the separate GTE GTP_UA, GTP_UB are mappedonto corresponding radio access bearers RABa, RABb. Accordingly, each ofthe radio access bearers and the GTP established for each of the firstand second UEs UEa, UEb can specify a different quality of service QoSa,QoSb. Thus, there is a one to one mapping between the radio accessbearer and the GTP. FIG. 7 is therefore an example of a common PDPcontext but using different GPRS bearers.

An alternative arrangement is shown in FIG. 8 in which the first andsecond UEs UEa, UEb which have established a common PDP context utilisea common GPRS bearer. As such there is no distinction of the GTPestablished by the gateway support node 6. That is to say the GPRSbearer is shared between the first and second UEs UEa, UEb. In order tocorrectly communicate internet packets across the GPRS network via theradio access interface established by the RNC, the RNC must identifyinternet protocol packets, which are destined for either the first UEUEa or the second UE UEb. To this end, the RNC is provided with a radioaccess bearer filter 200. The radio access bearer filter 200 receivesthe internet packets from the GTP_U and identifies an appropriate one oftwo radio access bearers RABa, RABb from which and to which the firstand second UEs UEa, UEb communicate internet packets respectively. Inorder to filter the internet packets correctly onto the appropriateradio access bearers RABa, RABb, the RAB filter 200 is provided with adestination address of the first and second UEs UEa, UEb. Thus, asillustrated in FIG. 8, the RAB filter 200 identifies the destinationaddress in the header of the internet protocol packet 202 received inthe GTP units 204. In accordance with the destination address for thefirst or the second UEs UEa, UEb, the RAB filter filters the internetprotocol packets to the appropriate bearer for delivery to thecorresponding UE UEa, UEb.

Providing Different Quality of Service on a Common GPRS Bearer

FIG. 9 provides an illustrative representation of an arrangement bywhich different quality of service can be provided to the communicationof internet packets via a common GPRS bearer. For example, onecommunications session may be communicating internet packets inaccordance with Web browse, whereas another communications session maybe communicating interne packets in accordance with voice over internetprotocol. In accordance with the present technique differing quality ofservices are achieved by mapping a differential service quality ofservice (QoS) class provided within the IETF internet protocol standardonto an appropriate quality of service for communication across the GPRScore network. As those acquainted with the internet protocol standardsv6 and v4 will appreciate, the differential service QoS provided withinthe IETF standard has three categories which are Expedited Forwarding(EF) Assured Forwarding (AF) and Best Effort (BE). As shown in FIG. 9internet packets IPa, IPb which are being communicated to either thefirst or the second UEs UEa, UEb 220, 224 are received at the gatewaysupport node 6. In each of the respective headers of the interne packetsIPa, IPb, 220, 224 is provided a differential service QOS. For theexample shown in FIG. 9, the differential service QoS for the firstinternet packet destined for the first UE IPa 220 is EF whereas thedifferential service QOS for the second internet packet destined for thesecond UE IPb 224 is AF. The gateway support node 6 is arranged to forma GTP filter which is operable to map the differential service QoSs EFand AF into an appropriate quality of service QoSa, QoSb forcommunication across the core network to the RNC. The quality of serviceprovided by the GTP_U QoSa, QoSb may be the same as the EF and AFaccording to the IETF standards, or maybe an alternative differential inquality of service class. The first and second internet packets IPa, IPb220, 224 are then communicated via the transport IP layer to the RNC.

As shown in FIG. 9 communication between each of the core networkelements gateway support node, SGSN 42 to the RNC 60, is via differentprotocol levels. These are a higher level end to end interne protocollevel 240, a GTP_U internet protocol level 242, a UDP layer 244 and aninternet protocol transport layer 246. Thus, the gateway support node 6is arranged to communicate the internet packets via the transportinternet protocol layer using quality of service QoSa, QOSb identifiedfrom the differential quality of service AF, EF identified in theheaders of each of the packets for communication to the respective firstand second UEs UEa, UEb.

When the internet packets are received at the RNC, then the RAB filter200 operates in a corresponding way to that explained with reference toFIG. 8 to pass the packets from each of the internet protocol transportlayers to the appropriate radio access bearer RABa, RABb. Theappropriate radio access bearers are identified by the destinationaddress of the first or second user equipment UEa, UEb. In accordancewith the present technique the UEs are arranged to establish a RABfilter, when the common PDF context is established. Therefore in ananalagous way in which the TFT is established, each UE sets up anappropriate component in the RAB filter, so that the internet packetsreceived from the transport IP layer can be filtered to the appropriateradio access bearer.

Various further aspects and features of the present invention aredefined in the appended claims. Various modifications can be made to theembodiments herein described without departing from the scope of thepresent invention.

1. A packet radio communications system for communicating internetpackets to and/or from mobile user equipment, the system comprising acore network comprising a plurality of packet data networks, eachincluding network communications elements operable to communicateinternet packets using an internet protocol transport plane, and acommon gateway support node, the gateway support node being operable toroute the internet packets via communications bearers establishedthrough the packet data networks using the network communicationselements, a plurality of radio access networks connected by the internetprotocol transport plane to the core network components of the packetdata networks for communicating the internet protocol packets to and/orfrom the mobile user equipment, each of the radio access networks beingoperable to provide radio access bearers for communicating the internetpackets to and/or from the mobile user equipment, a packet servicecontrol subsystem function comprising an access network part and anon-access network part, the access network part being arranged tocontrol the communication of the internet packets via the radio accessbearers and the non-access network part being arranged to control thecommunication of the internet packets via the communications bearersusing the network communications elements of the packet data networks,wherein at least one of the plurality of packet data networks isarranged to operate in accordance with a different telecommunicationsstandard than the other packet data networks and wherein the packetservice control subsystem function is operable to provide differentqualities of service as requested in the internet packets' header. 2.The packet radio communications system as claimed in claim 1, whereinthe common gateway support node is operable to establish common packetcommunications bearers via the packet data communications networks andthe radio access networks, the common packet data communications bearersbeing arranged to communicate internet packets to and/or from mobileuser equipment using a plurality of different internet protocols.
 3. Thepacket radio communications system as claimed in claim 2, wherein thecommon gateway support node is operable to establish in combination withthe network communications elements common packet data protocol contextfor providing resource allocation control and connection of the internetpackets communicated via the common packet data communications bearers.4. The packet radio communications system as claimed in claim 2, whereinthe common packet data communications bearers are shared by more thanone mobile user equipment.
 5. The packet radio communications system asclaimed in claim 1, wherein at least one of the radio access networks isarranged to operate in accordance with a different telecommunicationsstandard than the other radio access networks.
 6. A method ofcommunicating internet packets to and/or from mobile user equipmentusing a packet radio communications system, the system comprising a corenetwork, a plurality of radio access networks and a packet servicecontrol subsystem function, the core network comprising a plurality ofpacket data networks, each including network communications elements forcommunicating internet packets using an internet protocol transportplane, and a common gateway support node, the plurality of radio accessnetworks being connected by the internet protocol transport plane to thepacket data networks, the method comprising establishing communicationsbearers through the transport plane of the packet data networks usingthe network communications elements, routing the internet packets viathe established communications bearers, providing radio access bearersusing the plurality of radio access networks connected by the internetprotocol transport plane to the core network components of the packetdata networks, communicating the internet packets to and/or from themobile user equipment via the radio access bearers, controlling thecommunication of the internet packets via the radio access bearers usingthe access network part of the packet service control subsystemfunction, and controlling the communication of the internet packets viathe communications bearers using the non-access network part of thepacket service control subsystem function, wherein at least one of theplurality of packet data networks is arranged to operate in accordancewith a different telecommunications standard than the other packet datanetworks and the communication session is controllable to providedifferent qualities of service as requested in the internet packets'header.
 7. An apparatus for communicating internet packets to and/orfrom mobile user equipment using a packet radio communications system,the system comprising a core network, a plurality of radio accessnetworks and a packet service control subsystem function, the corenetwork comprising a plurality of packet data networks, each includingnetwork communications elements for communicating internet packets usingan internet protocol transport plane, and a common gateway support node,the plurality of radio access networks being connected by the internetprotocol transport plane to the packet data networks, the methodcomprising means for establishing communications bearers through thetransport plane of the packet data networks using the networkcommunications elements, means for routing the internet packets via theestablished communications bearers, means for providing radio accessbearers using the plurality of radio access networks connected by theinternet protocol transport plane to the core network components of thepacket data networks, means for communicating the internet packets toand/or from the mobile user equipment via the radio access bearers,means for controlling the communication of the internet packets via theradio access bearers using the access network part of the packet servicecontrol subsystem function, means for controlling the communication ofthe internet packets via the communications bearers using the non-accessnetwork part of the packet service control subsystem function byactivating a packet data communication bearer suitable for supporting acommunication session corresponding to the communication of the internetpackets to and/or from the one or more mobile user equipment, and meansfor controlling the different qualities of service of the communicationsession as requested in the internet packets' header, wherein at leastone of the plurality of packet data networks is arranged to operate inaccordance with a different telecommunications standard than the otherpacket data networks.
 8. (canceled)
 9. (canceled)
 10. The packet radiocommunications system as claimed in claim 3, wherein the common packetdata communications bearers are shared by more than one mobile userequipment.
 11. The packet radio communications system as claimed inclaim 2, wherein at least one of the radio access networks is arrangedto operate in accordance with a different telecommunications standardthan the other radio access networks.
 12. The packet radiocommunications system as claimed in claim 3, wherein at least one of theradio access networks is arranged to operate in accordance with adifferent telecommunications standard than the other radio accessnetworks.
 13. The packet radio communications system as claimed in claim4, wherein at least one of the radio access networks is arranged tooperate in accordance with a different telecommunications standard thanthe other radio access networks.
 14. The packet radio communicationssystem as claimed in claim 10, wherein at least one of the radio accessnetworks is arranged to operate in accordance with a differenttelecommunications standard than the other radio access networks.